1. Field of the Invention
The present invention relates to controls for vehicular automated mechanical transmission systems and, in particular, to controls for vehicular automated mechanical transmission systems having a fully automatic mode of operation wherein shifts are automatically selected and implemented and a semi-automatic mode of operation wherein manual selection of upshifts and downshifts from a currently engaged ratio is required and manually selected shifts are, if allowable, automatically implemented.
2. Description of the Prior Art
Fully automatic vehicular automated mechanical transmission systems wherein shifts are automatically selected and automatically implemented are well known in the prior art. Typically, such systems include a microprocessor-based controller which receives various input signals from sensors, such as signals indicative of engine and/or vehicle speed and of throttle pedal position, and processes same according to predetermined logic rules to issue command output signals to various system actuators, such as a transmission operator, a master clutch operator and/or an engine fuel controller. Examples of such fully automatic systems may be seen by reference to U.S. Pat. Nos. 3,961,546; 4,361,060; 4,595,986; 5,063,511; 5,109,729; 5,293,316; 5,305,213; 5,305,240 and 5,435,212, the disclosures of which are incorporated herein by reference.
Many vehicle operators, particularly operators of large, heavy-duty vehicles, like to control the selection of the gear ratios, particularly since they can see and/or know the nature of the road ahead and/or of the load being carried. This preference has been satisfied by the provision of a semi-automatic vehicular automated mechanical transmission control wherein automatic changing between a plurality of gear ratios is provided, while normally permitting the vehicle operator to choose when to make a particular gear ratio change and, preferably, whether to select the immediately consecutive ratio up or down or, by repetitive pulses in a given direction, to skip one or more ratios. Examples of such semi-automatic vehicular automated mechanical transmission systems may be seen by reference to U.S. Pat. Nos. 4,648,290; 4,800,360; 4,930,078 and 4,930,081, the disclosures of which are incorporated herein by reference.
While the foregoing automatic and semi-automatic mechanical transmission systems do provide desirable automated mechanical transmission control, the controls were subject to improvement in the area of allowing the vehicle operator to select operation in either the fully automatic or the semi-automatic mode of operation and/or did not allow the operator to quickly switch from one mode of operation to the other during vehicle operation.